Poll after poll predicted the Remain vote would win the day and there would be no Brexit. Almost all of them got it wrong. Thursday’s referendum left the UK preparing to leave the European Union, and many pollsters wondering what went wrong with their efforts to gauge public sentiment.

David Rothschild, a researcher at Microsoft and Columbia University who runs PredictWise, a site dedicated to prediction markets was quoted in the article that “Pollfish…surfaced a nugget of data that almost everyone else missed: The attitudes of undecided votes looked almost identical to Leave voters.”